Rabbi Simlai made one of the most ambitious claims in the entire Talmud. He said: 613 commandments were given to Moses at Sinai—365 prohibitions corresponding to the days of the solar year, and 248 positive commandments corresponding to the limbs of the human body. Then he traced a breathtaking arc of compression.
David came and reduced the 613 to eleven principles, listed in (Psalms 15): walk wholeheartedly, work righteousness, speak truth in your heart, do not slander, do not harm your neighbor, do not take a bribe. The Talmud in Tractate Makkot identifies a real person behind each principle. "Works righteousness"—that is Abba Chilkiyyahu, who would not pause from his labor even to greet passersby. "Speaks truth in his heart"—that is Rav Safra, who was reciting the Shema when a buyer offered him a price. He mentally accepted the offer but could not respond. When the buyer raised his offer, Rav Safra insisted on selling at the original, lower price. He had already agreed in his heart.
Isaiah came and reduced the eleven to six (Isaiah 33:15). Micah reduced them to three (Micah 6:8): "Do justice, love mercy, and walk humbly with your God." Isaiah returned and compressed further to two (Isaiah 56:1): "Keep justice and do righteousness." Amos reduced everything to one (Amos 5:4): "Seek Me and live."
But Habakkuk gave the final formulation. He took all 613 commandments and stood them on a single foundation (Habakkuk 2:4): "The righteous person shall live by his faith."
Six hundred and thirteen laws. Compressed to eleven. Then six. Then three. Then two. Then one. The entire Torah balanced on a single word: faith.